How to plasterboard a ceiling

Video by Tommy's Trade Secrets. This walk-through is based on the video "Tommy's Trade Secrets - How to Plasterboard a Ceiling" from Tommy's Trade Secrets, which follows Andy plasterboarding an extension ceiling using 8 x 4 sheets. It is well worth watching before you start — the section on supporting the boards while fixing is particularly useful if you are working alone or with only one helper.

1. Choose the right board and check your joist centres

For most domestic ceilings, 12.5 mm standard plasterboard in 2400 x 1200 mm (8 x 4) sheets is the go-to choice. If you are planning to skim plaster over the top, standard grey-face board is fine. If you want to tape and joint instead, use tapered-edge board so the joints sit slightly recessed and can be filled flush.

Before you order anything, check your joist centres. They should be either 400 mm or 600 mm apart. If they are at 400 mm, a 12.5 mm board is adequate. At 600 mm centres, consider going up to 15 mm board — it is heavier but it will not bow between fixings. Also check that the joists are level with each other; any that have dropped or twisted need packing out before you start or your ceiling will look like a gentle hillside.

2. Mark joist positions on the walls

Mark the position of every joist on the walls at both ends of the room before any boards go up. Once the first sheet is in place, you cannot see through it to find the joists — and screwing blind is a lottery. A string line snapped across the underside of the joists can help you check they are all at the same level too.

It is also worth marking the joist centres on the wall in pencil so you can extend those lines across the face of each board as you go. That way you always know exactly where to put your screws. Sounds obvious, but it is the kind of thing that gets skipped in a rush and causes problems later.

3. Plan your sheet layout and cut boards to size

Start from the centre of the room and work outwards so that any cut edges end up near the walls where they will be hidden by coving or a shadow gap. Lay out your sheets in a staggered, brick-bond pattern — never line up the joints from one row to the next, as that creates a weak line across the ceiling.

Cut boards with a sharp Stanley knife and a straight edge. Score the face, snap the board away from you over a batten, then run the knife down the back paper to separate. The cut edge will be rough; a rasp or surform takes the worst of it off. For tight cuts around light fittings or noggins, a jab saw is quicker than a knife. Mind you, keep cut edges away from joist positions — every sheet edge needs to land on timber to be screwed off properly.

4. Build or borrow a board lifter — or make a deadman

A full 8 x 4 sheet of 12.5 mm plasterboard weighs around 22 kg. Holding it against the ceiling while someone else drives screws is extremely hard work, and doing it solo is miserable. A proper board lifter (sometimes called a panel lift or drywall jack) is the right tool for the job — you can hire one from most tool-hire shops for around £30–£40 a day.

If you cannot get hold of one, a “deadman” — a T-shaped prop made from timber that wedges the board up while you screw — is the traditional workaround. It is fiddly, but it works. To be fair, even with a helper the lift is tiring; take your time and do not rush the fixing stage just because your arms are aching.

5. Fix the boards with the correct screws at the right centres

Use 42 mm drywall screws for 12.5 mm board fixed to timber joists. Drive them at 150 mm centres along sheet edges and 200 mm centres in the field (the middle of the board). Each screw head should dimple just below the surface of the board without breaking through the paper face — that takes a little practice but soon becomes second nature with a drywall screwdriver or a drill set to the right depth-stop.

Do not use nails. They work loose over time with the natural movement of timber, and before long you will see nail-pops appearing through your freshly decorated ceiling. Screws do not do that. Also, keep screws at least 10 mm in from the edge of a board to prevent the corner crumbling.

6. Fill joints and screw dimples ready for finishing

Once all the boards are up, the joints between sheets and the rows of screw dimples need to be dealt with before any skimming or decoration. If you are skimming, the plasterer will handle the prep — just make sure the boards are secure and any badly broken edges are trimmed back. If you are taping and jointing the ceiling yourself, see the separate guide on this site for that process.

Either way, give the whole ceiling a coat of PVA primer or plasterboard sealer before any finish coat goes on. Bare plasterboard is highly absorbent and will suck the moisture out of plaster or paint so fast it will crack or look patchy. One good coat of diluted PVA (about 5:1 water to PVA) will sort that out.

When to call a handyman

Call Richard if the ceiling area is large or awkward, if the existing ceiling needs to come down first, or if the joist spacing is irregular and needs extra noggins fitted before boarding can start. Working overhead for hours is also genuinely exhausting, and a botched ceiling that needs pulling down and redoing costs more in materials than getting it done right the first time. If you are in Sandwich or the surrounding East Kent area, give Richard a call and he can take a look.